1. Field of the Invention
The present invention relates to a color scanner of a plane scanning (flat bed) type of a high speed and a high efficiency, and more particularly to the color scanner comprising the steps of reading a color image to obtain and store the image data by pre-scanning for rough scanning, setting condition parameters to read and process the original by main scanning for detailed scanning, and recording effectively the image of the color original on a photosensitive material to produce printing plates.
2. Description of the Prior Art
According to one of the conventional methods for manufacturing each color separation plate of a plurality of original color images, each original image is halftoned by a predetermined number of times by means of a color scanner so as to produce a color separation film, a mask plate produced in a different process and the halftoned color separation film are laid-out on adhered to a layout sheet, and the layout sheet is exposed to light. However, the conventional method for manufacturing color separation plates has disadvantages, such as many processing steps, a necessity of skilled craftmen for precisely positioning and adhering the color separation film at the predetermined places of the layout sheet, much time, much laborous and skillful work, and much material.
There is another conventional method for reproducting the color image, in which method a plurality of original images respectively are printed in color by the predetermined number of times, the reproduced original images are cut out in the predetermined shape of an image on a predetermined block copy, the cut out image are laid-out and adhered on the predetermined positions of the block copy board. However, because the conventional method uses a photographic technique, it is not possible to freely change a color correction processing, a sharpness emphasis, and gradation conversion. The result being poor image quality. In addition, there has been an apparatus output-layouting simultaneously square images through a plurality of input apparatus (refer to, for example, Japanese Patent Publication No. 31762/1977). The conventional apparatus for outputting a square image has numerous disadvantages, namely, it is difficult to correspond to all or any shapes of the image, it requires laborious work for producing the mask plate, and it requires a plurality of input scanning section to be used to input the color original.
Recently, a layout retouch system (which is so called as a total system for plate making process of the printing industry) has been proposed, in which system the images are input through a digitizer in order to display images and patterns on a color CRT. The color original image is color-scanned with a designated magnification and the scanned image is stored in a memory device after A/D-converting. Then, the stored color original image information is displayed on the color CRT according to the input image information, the displaying image is edited in a main memory device of a computer through an interactive input system and then the resultant is again stored in a magnetic disc or the like with a format corresponding to the outputted display. Next, the color image information corresponding to the display or scene edited and outputted is D/A-converted and input to the output control circuit of a color scanner in order to obtain the desired layout image. The layout retouch system above necessitates disadvantageously a memory medium of such capacity for storing the information of the color original image and a high speed computer for editing or processing the information, resulting in increased cost of the whole construction of the system, and a time increase for editing or processing the information.
Another conventional system for inputting and outputting the image, which has been improved to solve the shortcomings mentioned above, is shown in FIG. 1 and described in Japanese Patent Laid-open No. 11062/1984. According to the conventional system shown in FIG. 1, a color original 2 applied on a rotary input drum 1 is output as an image on a recording material, for example, a color paper 11 pasted on an output drum 10, which rotating is according to the image information input through a digitizer 14 of an image input apparatus. In the image input/output system above, the color original 2 is color-scanned by a reading head 21 in order to separate in color and the color separation signal CS obtained is input to a logarithmic converting circuit 3. The color separation signal CS is converted to density signals DN through the logarithmic converting circuit 3 and then it is converted to digital density signal DS by an A/D converter 4. The digital density signal DS is input to a signal processing section 5 and a microprocessor 12. In the signal processing section 5, a color correction processing a sharpness emphasis and a gradation conversion are carried out, the color-processed image information DSA is converted to analog signals through a D/A converter 6 and input to a modulator 8 installed in a laser beam printer in order to modulate a laser beam emitted from a laser oscillator 7 and exposes the color paper 11 pasted on the output drum 10 by means of an output head (not shown).
While, it is necessary to install in the system a console 16 provided with a keyboard through which data and commands are input. According to the conventional system, the data and commands or instructions input through the console 16 are input to the computer 13 for processing these data, and commands outputting information and the information is displayed on an interactive graphic display 15. The computer 13 is connected to the microprocessor 12 of a lower-level system, the microprocessor 12 receives the density signal DS output from the A/D converter 4, and is further connected to the signal processing section 5 in order to function the process. The computer 13 and the microprocessor 12 constructs a computer system and the system displays the instruction for the operator and the like on the graphic display 15 according to the stored programs. The positions of the input drum 1 and the output drum 10 are respectively detected by detectors (not shown) and the positional information is input into a motion control section 9. The microprocessor 12 is adapted to be connected to the motion control section 9 so as to relatively drive and control the positional relationship of the input drum 1 and the output drum 10. The digitizer 14 has an original coordinate and X-Y axes of its own. The origin coordinate can be easily to any points, and X-Y axes can easily rotate by processing the signal. The corresponding relationship between the image position on the input drum 1 and the digitizer 14 is determined by installing guides, such as pins at the common plural position. The digitizer 14 is connected to the computer 13 to which the shape of the images and the desired positional coordinates are input.
In the image input/output system shown in FIG. 1, it is noted that the color original 2 is pasted, when it is read, directly to the smooth outer face of the cylindrical input drum 1 as shown in FIG. 2, which drum being made of acrylic resins, glass or the like. The input drum 1 has a light source 20 therein and the light source illuminates the color original 2 and the light beam LT passes through the cylindrical wall of the input drum 1. The reading head 21 situated outside of the input drum 1 receives the passed light beam LT, so that the image of the color original 2 is input to the reading head 21. In the condition, it there is a space or gap to a length of about a wavelength of the beam of the light source 20 between the color original 2 and the input drum 1, a Newton ring (interference fringe) is formed by an interference phenomenon happened on the surface between the rear face of the color original 2 and the front face of the input drum 1, so that the Newton ring is appeared on the color original 2 in the shape of stripes or density irregularity, thus deteriorating the quality of the original considerably.
According to the conventional method, in order to prevent the interference stripes from forming, super particle powder has been scattered or applied between the color original 2 and input drum 1, or filling agent is coated on the cylindrical input drum 1. However, the fine particle powder has disadvantages, such as the outlines of particles are clearly seen when the multiplication of the image is high and the powder is troublesome to handle. The filling agent also has shortcomings, such as the application or coating and removing or wiping-out of the filling agent is very difficult to completely do.
It is known that the image input/output system of the prior art receives an image information on the original film and the like, functions to enlarge/reduce the image, and outputs the image with any layout on the display or some output devices. The image/output system must know or determine the coordinates of the color original 2 on the input drum 1 in order to layout the image during the reading of the original as shown in FIG. 2. Consequently, as shown in FIG. 3, the color original 2 is pasted on the original pasting base 22 of transparent and square-shaped sheet having a thickness of about 100 .mu.m by pasting tapes 23. Positioning holes 24 formed in the original pasting base 22 are fitted onto the corresponding pins of the digitizer 14 so as to input the coordinates of the particular or necessary portion of the color original 2 to the image input/output system. Then, the positioning holes 24 of the original pasting base 22 are fitted securely onto the corresponding pins 25 planted on the input drum 1 as shown in FIG. 4. As next step, the light source 20 in the interior of the input drum 1 as shown in FIG. 2, irradiates the color original 2 and the reading head 21 receives the passed light beam LT through the drum wall and the color original 2, so that the image of the color original 2 is input to the reading head 21. The input image is compared to the coordinates input by the digitizer 14 so as to layout the image.
Furthermore, the conventional color scanner necessitates expert operators determining and setting the separating conditions and signal processing conditions and the time used to the condition determination is considerably longer than that of the system for which time the system actually processes the separating operation and the signal processing. Then, operation of the conventional color scanner is complicated, so that psychological burden upon the operator is very heavy.
A color separation scanner, which processes the color original by the plane scanning method with the application of the TV camera, has appeared so as to solve the defects of drum type color scanner above mentioned, however, for operating this kind of apparatus practically the system has problems in increasing the speed and efficiency of data reading process, and the operation for setting the parameters of this type of color scanner is still complicated.